Effect of synthesis method on solvation and exfoliation of graphite oxide

The structure of graphene oxide membranes in liquid water, ethanol and water–ethanol mixtures

“…However, the lamellae in B-GO membrane are densely packed and rather parallel to each other, whereas in H-GO they are non-planar in shape: corrugated in wave-like formations and separated form each other by larger free spaces. It can be suggested that H-GO flakes are in more defect state compared to B-GO which is also consistent with weaker and broader d(001) reflections as revealed by XRD on powder samples 11 and diffuse scattering recorded for membranes (see below). The free spaces between GO lamellae observed in Figure 2 can be filled with water or other solvents upon immersion into liquid, which is important for discussion of results reported below.…”

“…Humidity-dependent studies of graphene oxide membranes 21 and paper-like materials 20 structure have been reported recently, but no structural data are available for liquid solvents. Hydration and solvation properties of precursor powder graphite oxides have been reported in our earlier studies 11,[28][29][30][31][32][33] but it is an open question to which extent these results can be applied to the GO membranes. The most striking observation is that Hummers graphite oxide powder can be intercalated by three monolayers of water (interlayer distance d(001)=12.4Å at ambient temperature), 12,35 2-3 monolayers of methanol or ethanol (d(001)=15.5Å) at ambient conditions and up to four monolayers at low temperatures (d(001)=20.6Å) 33 .…”

“…Detailed characterization of Brodie and Hummers graphite oxides used here as precursors for preparation of B-GO and H-GO membranes is available elsewhere 11 . The synthesis of the membranes included three steps.…”

“…3,[6][7][8][9] It is important to note that graphite oxides synthesized using Brodie and Hummers methods (B-GO and H-GO) are different materials not only in respect to hydration/solvation but also exfoliation properties. [10][11] In fact, many different kinds of graphite oxides with strong variation of oxidation degree can be synthesized. 12 Graphite oxides synthesized by different methods demonstrate also difference in types and relative numbers of functional groups attached to GO sheets.…”

“…No reports on synthesis and properties of Brodie GO membranes are available to the moment. Significant variation of the membrane properties depending on type of precursor graphite oxide could be expected taking into account different hydration and solvation properties of precursor B-GO and H-GO in powder form 11 . Surprisingly, no structural studies of solvent immersed GO membranes have been reported so far.…”